There is a total of 359 clues beginning with ef
- Effective range
 - Effective range of a loud-speaker
 - Effective relievers
 - Effective resource held in reserve: Colloq
 - Effective salesman
 - Effective salesperson
 - Effective spacing of gags
 - Effective use
 - Effective use of lang
 - Effective, as a law
 - Effective, as a rule
 - Effective, as an argument
 - Effective
 - Effective; vigorous
 - Effectively
 - Effectively concise
 - Effectively play reveille
 - Effectively slam on the brakes
 - Effectively treat
 - Effectiveness
 - Effectiveness of a coat at the beach?: Abbr
 - Effectiveness of a law, metaphorically
 - Effectiveness of a satisfactory comic insult?
 - Effectiveness of a weapon
 - Effectiveness, figuratively
 - Effectiveness
 - Effects
 - Effects by force
 - Effects created by 43-Across
 - Effects in music
 - Effects ingress
 - Effects of double espressos
 - Effects of many waterfalls
 - Effects of months of glute workouts?
 - Effects of riddling
 - Effects of Southern exposure?
 - Effects seen down the road
 - Effects seen on FX, perhaps
 - Effects used to create some superheroes
 - Effects used to create the movie Hulk (abbr)
 - Effectuate
 - Effectuates
 - Effeminacy
 - Effeminate
 - Effendi's equivalent
 - Effendi, for one
 - Effervesce
 - Effervesce, as some wine
 - Effervesce
 - Effervesced
 - Effervesced
 - Effervescence
 - Effervescence
 - Effervescent
 - Effervescent "Dr"
 - Effervescent "Dr"
 - Effervescent beverage
 - Effervescent beverages
 - Effervescent citrus beverage
 - Effervescent doctor?
 - Effervescent dosage
 - Effervescent drink
 - Effervescent drink
 - Effervescent drinks
 - Effervescent drinks
 - Effervescent item tossed into tubs
 - Effervescent refreshment
 - Effervescent sound
 - Effervescent tonic
 - Effervescent, perhaps
 - Effervescent-voiced birds
 - Effervescent-voiced songbird
 - Effervescent
 - Effervescent: Colloq
 - Effervescer
 - Effervesces
 - Effervesces
 - Effervescing
 - Effervescing device
 - Effete
 - Effete
 - Efficacious
 - Efficacy
 - Efficiency adage, in France?
 - Efficiency apartment
 - Efficiency check
 - Efficiency device
 - Efficiency expert's goal
 - Efficiency expert's task, briefly
 - Efficiency expert's tool
 - Efficiency experts
 - Efficiency experts earn a living ___
 - Efficiency improvers
 - Efficiency meas
 - Efficiency measure
 - Efficiency measurement
 - Efficiency option
 - Efficiency stat
 - Efficiency stat for NFL passers
 - Efficiency symbol, in physics