Spotted large number at church in past (7)
I believe the answer is:
blotchy
'spotted' is the definition.
(thesaurus)
'large number at church in past' is the wordplay.
'large number' becomes 'lot' (a large amount).
'at' is a charade indicator (letters next to each other).
'church' becomes 'ch' (common abbreviation).
'in' indicates putting letters inside.
'past' becomes 'by' (synonyms).
'lot'+'ch'='lotch'
'lotch' going inside 'by' is 'BLOTCHY'.
(Other definitions for blotchy that I've seen before include "Unevenly stained" , "Discoloured in patches" , "Marked with patches" , "With irregular skin discolouration" .)