In Eric's time our doctor insincere (12)

I believe the answer is:

meretricious

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'in' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?

'eric's time our doctor insincere' is the wordplay.
'doctor' is an anagram indicator.
'insincere' becomes 's' (I can't justify this - if you can you should believe this answer much more).
'eric'+'time'+'our'='erictimeour'
'erictimeour' with letters rearranged gives 'meretriciou'.
'meretriciou'+'s'='MERETRICIOUS'

Can you help me to learn more?

(Other definitions for meretricious that I've seen before include "Courier-Times (anag) - tacky" , "showily attractive" , "Flashy" , "Showy" , "Tawdry" .)

I've seen this clue in the Sydney Morning Herald.

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