Worker on wireless, mostly shining (7)
I believe the answer is:
radiant
'shining' is the definition.
(thesaurus)
'worker on wireless mostly' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'on' is a charade indicator (letters next to each other).
'wireless' becomes 'radio' ('radio' can be a synonym of 'wireless').
'mostly' means to remove the last letter.
'radio' with its final letter removed is 'radi'.
'ant' put after 'radi' is 'RADIANT'.
(Other definitions for radiant that I've seen before include "Glowing with joy" , "Sending out light, glowing" , "glowing with happiness" , "Splendid; heater type" , "Lit up" .)