On reflection, I'm a nudist removing cardigan, essentially - it's not desirable at the beach (7)
I believe the answer is:
tsunami
'on reflection' is the definition.
Both the answer and definition are singular nouns.
Perhaps there's a link between them I don't understand?
'i'm a nudist removing cardigan essentially it's not desirable at the beach' is the wordplay.
I cannot quite see how this works, but
'i'm' could be 'am' (I've seen this in other clues) and 'am' is found within the answer.
'it's' could be 'ts' (abbreviation. e.g. in 'tis) and 'ts' is found in the answer.
'not' could be 'un' (prefix meaning 'not') and 'un' is present in the answer.
A single letter 'i' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tsunami that I've seen before include "Freak wave" , "Large ocean wave" , ""Harbour wave"" , "Long sea wave" , "Large sea wave caused by an earthquake" .)