Muck around when a coverlet's edging out of bed (3,2)
I believe the answer is:
act up
'muck around' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how one could define the other.
'a coverlet's edging out of bed' is the wordplay.
'edging' means to remove the middle letters (edging means the letters on the edges).
'out of bed' becomes 'up' (synonyms).
'coverlet' with its middle taken out is 'ct'.
'a'+'ct'+'up'='ACT UP'
'when' is the link.
Can you help me to learn more?
(Other definitions for act up that I've seen before include "Give trouble, make a fuss" , "Informally, behave badly or cause trouble" , "Behave badly, give trouble" , "Become unpleasant" , "go wrong" .)