Insect repellent used by Tom returning pencil to everyone (8)
I believe the answer is:
mothball
'insect repellent' is the definition.
(I've seen this before)
'tom returning pencil to everyone' is the wordplay.
'returning' says the letters should be written in reverse.
'pencil' becomes 'hb'.
'to everyone' becomes 'all' (all people).
'tom' back-to-front is 'mot'.
'mot'+'hb'+'all'='MOTHBALL'
'used by' is the link.
(Other definitions for mothball that I've seen before include "put on back burner" , "Insect repellent" , "Put under wraps" , "Lay aside indefinitely" , "Put on ice" .)