Farm worker, or a writer about love (4)
I believe the answer is:
peon
'farm worker' is the definition.
(peon can mean an unskilled farm worker)
'a writer about love' is the wordplay.
'a writer' becomes 'pen' (something which writes).
'about' means one lot of letters goes inside another.
'love' becomes 'o' (love means zero in tennis).
'pen' placed around 'o' is 'PEON'.
'or' is the link.
(Other definitions for peon that I've seen before include "A Mexican peasant or labourer" , "Spanish-American farm labourer" , "Spanish-American menial worker" , "Latin American farm labourer" , "lowly farm worker" .)