Figure the mule ran off (7)
I believe the answer is:
numeral
'figure' is the definition.
(a numeral is a figure representing a number)
'mule ran off' is the wordplay.
'off' is an anagram indicator.
'mule'+'ran'='muleran'
'muleran' with letters rearranged gives 'NUMERAL'.
'the' is the link.
(Other definitions for numeral that I've seen before include "Figure representing an integer" , "Figure denoting a number" , "Affable and sociable" , "Figure or symbol like '1', for example" , "Eg, two or seven" .)