Gents arranged to hide, say, savings (4,3)
I believe the answer is:
nest egg
'savings' is the definition.
(nest egg can mean someone's savings)
'gents arranged to hide say' is the wordplay.
'arranged' indicates an anagram.
'to hide' indicates putting letters inside.
'say' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'gents' anagrammed gives 'nestg'.
'nestg' going around 'eg' is 'NEST-EGG'.
(Other definitions for nest egg that I've seen before include "Sum of money saved in avian manner" , "Fund put by as a reserve" , "Savings kept in reserve" , "Reserve funds" , "a little money?" .)