Brings together a thousand donkeys (7)
I believe the answer is:
amasses
'brings together' is the definition.
(I've seen this in another clue)
'a thousand donkeys' is the wordplay.
'thousand' becomes 'm' (Roman numeral for a thousand).
'donkeys' becomes 'asses' (an ass is a donkey).
'a'+'m'+'asses'='AMASSES'
(Other definitions for amasses that I've seen before include "Collects" , "Gathers together" , "'Accumulates, gathers (7)'" .)