Dad's Army character, man that's very plain? (9)
I believe the answer is:
pikestaff
'very plain?' is the definition.
(I've seen this before)
'dad's army character man' is the wordplay.
I cannot really understand how this works, but
'army' could be 'ta' (abbreviation for Territorial Army) and 'ta' is found in the answer.
'character' could be 'pi' (pi is a kind of character) and 'pi' is found within the answer.
'man' could be 'k' (abbreviation for king, a chess man) and 'k' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for pikestaff that I've seen before include "that's very plain!" , "As plain as this is obvious" , "Proverbially plain handle of old weapon" , "Weapon on a pole" , "Mediaeval lance" .)