Laurel & Hardy's fourth feature put on to entertain wife - relax (5,4)
I believe the answer is:
stand down
'relax' is the definition.
Both the answer and definition are verbs in their base form.
Maybe you can see an association between them that I don't see?
'laurel hardy's fourth feature put on to entertain wife' is the wordplay.
'laurel' becomes 'stan' (comedian Stan Laurel is an example).
'hardy's fourth' becomes 'd' (4th letter of 'hardy').
'feature put on' becomes 'don' (I can't explain this - if you can you should give a lot more credence to this answer).
'to entertain' means one lot of letters goes inside another.
'wife' becomes 'w' (abbreviation).
'don' placed around 'w' is 'down'.
'stan'+'d'+'down'='STAND DOWN'
Can you help me to learn more?
(Other definitions for stand down that I've seen before include "Resign (from office)" , "Leave the witness box" , "Quit" , "Withdraw from post or competition" , "Withdraw; go off duty" .)