They prefer wide, open mouths with dimples having one small indentation in the middle (8)
I believe the answer is:
dentists
'they' is the definition.
Both the definition and answer are plural nouns.
Maybe there's an association between them I don't understand?
'prefer wide open mouths with dimples having one small indentation in the middle' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'i' (roman numeral) and 'i' is located in the answer.
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is found in the answer.
'indentation' could be 'dent' (synonyms) and 'dent' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dentists that I've seen before include "Tooth doctors" , "Orthodontists, periodontists etc." , "Professional carers for teeth" , "They care for teeth" .)