Flustered state following drink (4)
I believe the answer is:
flap
'flustered state' is the definition.
'flap' can be an answer for 'state' (I have seen 'State of panic' mean 'flap' so perhaps 'state' could also mean 'flap'). I'm not sure about the 'flustered' bit.
'following drink' is the wordplay.
'following' becomes 'f' (used when citing page numbers etc).
'drink' becomes 'lap' (to lap is to drink up).
'f'+'lap'='FLAP'
Can you help me to learn more?
(Other definitions for flap that I've seen before include "Panic; fold" , "Moving surface on wing" , "Tab - tizzy - move wings" , "State of agitation" , "Wave up and down - panic" .)