Very busy in that arid resort (4,2,2)
I believe the answer is:
hard at it
'very busy' is the definition.
(I've seen this before)
'that arid resort' is the wordplay.
'resort' indicates anagramming the letters.
'that'+'arid'='thatarid'
'thatarid' anagrammed gives 'HARD AT IT'.
'in' is the link.
(Other definitions for hard at it that I've seen before include "Working very busily" , "Very busy - that raid (anag)" , "Really busy" .)