Charge sat awkwardly -- go in uninvited (9)
I believe the answer is:
gatecrash
'go in uninvited' is the definition.
(to gatecrash is to attend an event uninvited)
'charge sat awkwardly' is the wordplay.
'awkwardly' indicates an anagram.
'charge'+'sat'='chargesat'
'chargesat' is an anagram of 'GATECRASH'.
(Other definitions for gatecrash that I've seen before include "to do so uninvited" , "Try to get in for free" , "join party unofficially" , "enter without invitation" , "join party if not wanted" .)