Old boy, impolite, taking time to butt in (7)
I believe the answer is:
obtrude
'butt in' is the definition.
(thesaurus)
'old boy impolite taking time' is the wordplay.
'old boy' becomes 'ob'.
'impolite' becomes 'rude' ('rude' can be similar in meaning to 'impolite').
'taking' indicates putting letters inside.
'time' becomes 't'.
'ob'+'rude'='obrude'
'obrude' enclosing 't' is 'OBTRUDE'.
'to' is the link.
(Other definitions for obtrude that I've seen before include "Make unpleasantly noticeable" , "Doubter (anag)" , "Interfere" , "Stick out unpleasantly" , "Thrust oneself forward" .)