Crossword Genius

What’s collapsed by spring in a heap — rot, sadly (5,3)

Ross

I believe the answer is:

opera hat

I'm a little stuck... Click here to teach me more about this clue!

'what's collapsed by spring' is the definition.
I can't judge whether this definition defines the answer.

'a heap rot sadly' is the wordplay.
'sadly' indicates anagramming the letters.
'a'+'heap'+'rot'='aheaprot'
'aheaprot' with letters rearranged gives 'OPERA-HAT'.

'in' acts as a link.

Can you help me to learn more?

(Other definitions for opera hat that I've seen before include "Headgear to hear 14dn" , "garment in theatre?" , "Formal theatre wear" , "Lid that collapses" , "collapsible accessory - atop him surely?" .)

I've seen this clue in The Times.
Want a hint initially instead of a full solution? Install my app