Spike Milligan finally getting merit (4)
I believe the answer is:
earn
'merit' is the definition.
(thesaurus)
'spike milligan finally getting' is the wordplay.
'spike' becomes 'ear' ('ear' can be a synonym of 'spike').
'finally' says to take the final letters.
'getting' says to put letters next to each other.
The last letter of 'milligan' is 'n'.
'ear'+'n'='EARN'
(Other definitions for earn that I've seen before include "Gain by working" , "Secure" , "and 3: Work for bed and board" , "Make - merit" , "long gone" .)