Thanks for the pointers to BL's Clark wills. There was a slight variation, probably just a transposition:

Manx Notebook : wife jony; son-i-law john sayle;
Shirley C Hogensen [Lawson microsite] : He left unto his son in law John Sayle and Joney his wife four pounds

I see that John Sayle married Gilbert's daughter in 1733(4):

23 Jan 1714 Jony d/o Gilt CLARK & Christin QUAYLE bapt KM [Manx Notebook cd]
16 Feb 1733 SALE Jon B'mainagh & CLERK Jony mar. KM [Manx Notebook cd]

I was surprised there was no mention of Gilbert's wife Christian even though she seemed to be still alive as far as I can tell.

I am consistently amazed by the amount of work you have done, compiling that vast collection of will summaries, marriage contracts, register transcriptions and everything else that is SO useful. Thank you!