Charlie enters transaction to get deposit (5)
I believe the answer is:
scale
'deposit' is the definition.
(eg limescale)
'charlie enters transaction' is the wordplay.
'charlie' becomes 'c' (phonetic alphabet: alpha, bravo, charlie etc.).
'enters' indicates putting letters inside.
'transaction' becomes 'sale' (sales are a type of transaction).
'c' put into 'sale' is 'SCALE'.
'to get' acts as a link.
(Other definitions for scale that I've seen before include "See 23" , "Plate protecting the skin of fish and reptiles" , "Series of notes in an octave" , "An ordered series of units for measurement purposes" , "Deposit in kettles, etc" .)