Feeler put out by worker upset girl (7)
I believe the answer is:
antenna
'feeler put out' is the definition.
(feeler put out by an insect)
'by worker upset girl' is the wordplay.
'by' means one lot of letters go next to another.
'worker' becomes 'ant' (worker is a type of ant).
'upset' says the letters should be written backwards.
'girl' becomes 'anne' (girl's name).
'anne' in reverse letter order is 'enna'.
'ant' put next to 'enna' is 'ANTENNA'.
(Other definitions for antenna that I've seen before include "Insect's feeler" , "could send out a message" , "Aerial - insect feeler" , "What detects signals" , "Transmitting aerial" .)