Set apart from one's love, in arrears (7)
I believe the answer is:
isolate
'set apart' is the definition.
(synonyms)
'one's love in arrears' is the wordplay.
'one's' becomes 'i's' (Roman numeral).
'love' becomes 'o' (love means zero in tennis).
'in arrears' becomes 'late' (similar in meaning).
'is'+'o'+'late'='ISOLATE'
'from' acts as a link.
(Other definitions for isolate that I've seen before include "Segregate. close off" , "Also tie (anag.)" , "Place or set apart" , "Detach" , "put away?" .)