Lose no orders and relax (6)
I believe the answer is:
loosen
'relax' is the definition.
(I know that relax can be written as loosen)
'lose no orders and' is the wordplay.
'no' becomes 'O' (O resembles 0).
'orders' is an anagram indicator.
'and' becomes 'n' (common abbreviation for 'and').
'lose'+'o'='loseo'
'loseo' is an anagram of 'loose'.
'loose'+'n'='LOOSEN'
(Other definitions for loosen that I've seen before include "Make less tight, slacken" , "Untie, relax" , "Work free" , "relax or tear apart" , "Relax the tension" .)