Maybe Tim's a hothead with this surname (5)
I believe the answer is:
smith
'this surname' is the definition.
(I have seen 'Common surname ' mean 'smith' so perhaps 'surname' could also mean 'smith')
'maybe tim's a hothead' is the wordplay.
'maybe' is an anagram indicator.
'a hothead' becomes 'h' (head letter of 'hot').
'tims' is an anagram of 'smit'.
'smit'+'h'='SMITH'
'with' is the link.
(Other definitions for smith that I've seen before include "Common family name" , "Bessie - - , blues singer" , "Worker in metals" , "Commonest name" , "Common English surname" .)