Sir means somehow to get close shave (4,4)
I believe the answer is:
near miss
'close shave' is the definition.
(I've seen this before)
'sir means somehow' is the wordplay.
'somehow' indicates anagramming the letters.
'sir'+'means'='sirmeans'
'sirmeans' is an anagram of 'NEAR MISS'.
'to get' is the link.
(Other definitions for near miss that I've seen before include "reason for alarm or relief on aircraft?" , "not a success" , "that doesn't quite hit the target" , "A narrowly avoided collision in seminars" , "Close to an accident" .)