Assistant in a team scratching head (4)
I believe the answer is:
aide
'assistant' is the definition.
(aide is a kind of assistant)
'a team scratching head' is the wordplay.
'team' becomes 'side' (both can mean a sports team).
'scratching head' means to remove the first letter (the word's head is removed).
'side' with its initial letter taken off is 'ide'.
'a'+'ide'='AIDE'
'in' is the link.
(Other definitions for aide that I've seen before include "someone in assistance" , "One to assist" , "Assistant to a more senior person" , "Officer who acts as military assistant" , "Second" .)