Second learner in club tends to talk incoherently (8)
I believe the answer is:
splutter
'to talk incoherently' is the definition.
(I've seen this before)
'second learner in club' is the wordplay.
'second' becomes 's' (common abbreviation).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'in' means one lot of letters goes inside another.
'club' becomes 'putter' (a golf club).
'l' inserted inside 'putter' is 'plutter'.
's'+'plutter'='SPLUTTER'
'tends' acts as a link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for splutter that I've seen before include "Eject drops" , "Make a series of spitting or choking sounds" , "Speak with a spitting sound" , "Speak indistinctly as in rage" , "Talk incoherently" .)