Panic-stricken following tirade by one Conservative (7)
I believe the answer is:
frantic
'panic-stricken' is the definition.
'following tirade by one conservative' is the wordplay.
'following' becomes 'f' (used when citing page numbers etc).
'tirade' becomes 'rant' (I've seen this before).
'by' means one lot of letters go next to another.
'one' becomes 'I' (Roman numeral).
'conservative' becomes 'C' (abbreviation commonly used in UK politics).
'f'+'rant'+'i'+'c'='FRANTIC'
(Other definitions for frantic that I've seen before include "Desperate with worry" , "having kittens" , "Excessively agitated" , "Berserk" , "Distraught with fear" .)