He greatly likes a cash surplus (5)
I believe the answer is:
lover
'he greatly likes a' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'cash surplus' is the wordplay.
'cash' becomes 'l' (The pound sterling symbol is an elaborate L).
'surplus' becomes 'over' (I've seen this before).
'l'+'over'='LOVER'
Can you help me to learn more?
(Other definitions for lover that I've seen before include "He really likes" , "Romantic partner" , "Devotee" , "One enjoys" , "Suitor" .)