Cancel bar crew days (11)
I believe the answer is:
countermand
'cancel' is the definition.
(countermanding is a kind of cancelling)
'bar crew days' is the wordplay.
'bar' becomes 'counter' (I've seen this before**).
'crew' becomes 'man' (I've seen this before).
'days' becomes 'd'.
'counter'+'man'+'d'='COUNTERMAND'
(Other definitions for countermand that I've seen before include "Revoke (an order)" , "Revoke; declare invalid" , "Recall" .)