Hotels cover the earth profusely (2,7)
'profusely' is the definition.
(profuse can mean in large numbers)
'hotels cover the earth' is the wordplay.
'hotels' becomes 'inns' (inn is a kind of hotel).
'cover' is an insertion indicator.
'the earth' becomes 'umber' (earthy pigment).
'inns' placed around 'umber' is 'IN NUMBERS'.