Engineers, cold, row and lean back (7)
I believe the answer is:
recline
'lean back' is the definition.
(synonyms)
'engineers cold row' is the wordplay.
'engineers' becomes 're' (abbreviation for Royal Engineers).
'cold' becomes 'C' (eg on taps).
'row' becomes 'line' (as in a row of things).
're'+'c'+'line'='RECLINE'
'and' acts as a link.
(Other definitions for recline that I've seen before include "Lean back, relax" , "Lie on the back or side" , "Lounge" , "Lie back and relax" , "Lie back and take it easy" .)