Old, dismal scent (5)

I believe the answer is:

odour

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'scent' is the definition.
(synonyms)

'old dismal' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'dismal' becomes 'dour' (I can't justify this - if you can you should believe this answer much more).
'o'+'dour'='ODOUR'

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(Other definitions for odour that I've seen before include "Olfactory sensation" , "Nasty smell" , "Smell, scent" , "Perfume" , "Regard" .)

I've seen this clue in The Times.

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