Put to use when I get into the fruit, Penny (7)
I believe the answer is:
applied
'put to use' is the definition.
(I've seen this before)
'i get into the fruit penny' is the wordplay.
'get into' is an insertion indicator.
'the fruit' becomes 'apple' (apple is a kind of fruit).
'penny' becomes 'd' (pre-decimalisation abbreviation for penny).
'i' put inside 'apple' is 'applie'.
'applie'+'d'='APPLIED'
'when' acts as a link.
(Other definitions for applied that I've seen before include "Administered" , "Put in (for a job) - not pure" , "Assigned < practical" , "Put into service, made work" , "Practical rather than theoretical" .)