One of the migrant mob that mingle madly around Minehead (7)
I believe the answer is:
lemming
'one of the migrant mob' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'mingle madly around minehead' is the wordplay.
'madly' is an anagram indicator.
'around' means one lot of letters goes inside another.
'minehead' becomes 'm' (head letter of 'mine').
'mingle' anagrammed gives 'leming'.
'leming' going around 'm' is 'LEMMING'.
'that' acts as a link.
Can you help me to learn more?
(Other definitions for lemming that I've seen before include "Supposedly suicidal animal" , "Rodent renowned for mass migration" , "Self-destructive follower" , "Rodent that follows others headlong over a cliff" , "Supposedly suicidal rodent" .)