Row about old Mike being offensive (7)
I believe the answer is:
noisome
'being offensive' is the definition.
('noisome' can be similar in meaning to 'offensive')
'row about old mike' is the wordplay.
'row' becomes 'noise' (I've seen this before).
'about' means one lot of letters goes inside another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'o'+'m'='om'
'noise' placed around 'om' is 'NOISOME'.
(Other definitions for noisome that I've seen before include "Foul-smelling, noxious" , "Foul-smelling - semi-Ono (anag)" , "Obnoxious" , "Odious" , "Harmful - noxious" .)