A clergyman's increases (4)

I believe the answer is:

adds

'increases' is the definition.
(to add to something is to increase it)

'a clergyman's' is the wordplay.
'clergyman's' becomes 'dds' (Doctor of Divinity).
'a'+'dds'='ADDS'

(Other definitions for adds that I've seen before include "Calculates the sum" , "Appends or increases" , "Aggregates or appends" , "Sums, totals" , "Appends; Totals" .)

I've seen this clue in The Globe and Mail.

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