Court order gets ambassador to squirm (6)
I believe the answer is:
'squirm' is the definition.
'court order gets ambassador' is the wordplay.
'court order' becomes 'writ' (I've seen this before).
'gets' says to put letters next to each other.
'ambassador' becomes 'he' (His or Her Excellency).
'to' acts as a link.
(Other definitions for writhe that I've seen before include "'Twist, squirm (6)'" , "Move sinuously" , "6, maybe in agony" , "Squirm in pain" , "worm" .)