Honest love for writer (4)
I believe the answer is:
open
'honest' is the definition.
(similar in meaning)
'love for writer' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'for' means one lot of letters go next to another.
'writer' becomes 'pen' (something which writes).
'o'+'pen'='OPEN'
(Other definitions for open that I've seen before include "gaping" , "Affording access" , "Candid - ready for business" , "Frank and unlocked" , "Not secret or hidden" .)