Dotty lent us one implement (7)
I believe the answer is:
utensil
'implement' is the definition.
(utensil is a kind of implement)
'dotty lent us one' is the wordplay.
'dotty' is an anagram indicator (a mad or 'dotty' version of the letters).
'one' becomes 'i' (Roman numeral).
'lent'+'us'+'i'='lentusi'
'lentusi' is an anagram of 'UTENSIL'.
(Other definitions for utensil that I've seen before include "Implement for practical use" , "Mandolin, perhaps" , "Let us in (anag) -- implement" , "vessel" , "Item, eg for kitchen" .)