Engineers get sloppy and take it easy (5)
I believe the answer is:
relax
'take it easy' is the definition.
(I've seen this in another clue)
'engineers get sloppy' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'get' says to put letters next to each other.
'sloppy' becomes 'lax' (both can careless).
're'+'lax'='RELAX'
'and' acts as a link.
(Other definitions for relax that I've seen before include "Abate" , "Loosen up, slow down" , "Hang loose" , "Chill out" , "Take it easy, don't be so tense" .)