Take it easy, about to get loose (5)
I believe the answer is:
relax
'take it easy' is the definition.
(I've seen this in another clue)
'about to get loose' is the wordplay.
'about to get' becomes 're' (I've seen this in other clues).
'loose' becomes 'lax' (synonyms).
're'+'lax'='RELAX'
(Other definitions for relax that I've seen before include "Moderate" , "Become less tense" , "Wind down" , "Unwind, take it easy" , "Make (rule) less strict" .)