Occasionally, magnet being near aerial ... (7)
I believe the answer is:
antenna
'aerial' is the definition.
(I know that aerial can be written as antenna)
'occasionally magnet being near' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'magnet'+'being'+'near'='magnetbeingnear'
The alternating letters of 'magnetbeingnear' are 'ANTENNA'.
(Other definitions for antenna that I've seen before include "Feature of dish" , "could send out a message" , "Feeling part" , "connected to 41?" , "Radio aerial" .)