Insect queen held up appendage (7)
I believe the answer is:
antenna
'appendage' is the definition.
(I know that antenna is a type of tentacle)
'insect queen held up' is the wordplay.
'insect' becomes 'ant' (ant is a kind of insect).
'queen' becomes 'anne' (Queen Anne, 18th-century queen).
'held up' says the letters should be written backwards.
'anne' written backwards gives 'enna'.
'ant'+'enna'='ANTENNA'
(Other definitions for antenna that I've seen before include "Insect's sensory appendage" , "receiver" , "one feels" , "Feature of dish" , "could send out a message" .)