Discharge PM with large following in home counties (7)
I believe the answer is:
spittle
'discharge' is the definition.
(fluid discharged from the mouth)
'pm with large following in home counties' is the wordplay.
'pm' becomes 'pitt' (I've seen this before).
'with large' becomes 'l' (I am not sure about the 'with' bit.).
'following' says to put letters next to each other.
'in' means one lot of letters goes inside another.
'home counties' becomes 'se' (Home Counties in the South East of England).
'pitt'+'l'='pittl'
'pittl' placed into 'se' is 'SPITTLE'.
(Other definitions for spittle that I've seen before include "bodily fluid" , "Saliva ejected from mouth." , "39 [SPITTLE]" .)