Nominally, he'd got upset about it (5)

I believe the answer is:

edith

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'nominally he'd got upset about it' is the definition.
The definition suggests a singular noun which matches the answer.

'he'd got upset about it' is the wordplay.
'got upset' is an anagram indicator (I've seen 'getting upset' mean this).
'about' means one lot of letters goes inside another.
'hed' is an anagram of 'edh'.
'edh' enclosing 'it' is 'EDITH'.

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(Other definitions for edith that I've seen before include "- Cavell, nurse executed in 1915" , "Dame - Sitwell, English poet (Facade)" , "Evans, Sitwell or Piaf" , "Osbert's sister" , "Woman" .)

I've seen this clue in the Evening Standard.

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