Crossword Genius

My lost puzzle, mainly (6)

Ross

I believe the answer is:

mostly

'mainly' is the definition.
(thesaurus)

'my lost puzzle' is the wordplay.
'puzzle' is an anagram indicator.
'my'+'lost'='mylost'
'mylost' is an anagram of 'MOSTLY'.

(Other definitions for mostly that I've seen before include "In large part" , "On the whole" , "In the main, nearly all" , "Largely" , "More often than not" .)

I've seen this clue in the Evening Standard.
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