Ray cheers supporting worker (5)
I believe the answer is:
manta
'ray' is the definition.
(I know that manta is a type of ray)
'cheers supporting worker' is the wordplay.
'cheers' becomes 'ta' (both can informally mean thank you).
'supporting' says to put letters next to each other (in a down clue, some letters go below others).
'worker' becomes 'man' (man is a kind of worker).
'ta' after 'man' is 'MANTA'.
(Other definitions for manta that I've seen before include "Giant ray" , "Devilfish" , "Kind of ray" , "Large ray" .)