Lift charge, one penny (6)
I believe the answer is:
fillip
'lift' is the definition.
(a fillip is a boost or lift)
'charge one penny' is the wordplay.
'charge' becomes 'fill' (I've seen this in other clues).
'one' becomes 'I' (Roman numeral).
'penny' becomes 'p' (short for pence).
'fill'+'i'+'p'='FILLIP'
(Other definitions for fillip that I've seen before include "As tonic" , "Incitement" , "give encouragement" , "Something adding stimulation" , "Stimulus or incentive" .)