Battle aircraftman taking ladies perhaps into Welsh lake (9)
I believe the answer is:
balaclava
'battle' is the definition.
(I've seen this before)
'aircraftman taking ladies perhaps into welsh lake' is the wordplay.
'aircraftman' becomes 'ac' (military abbreviation).
'taking ladies perhaps' becomes 'lav' (I can't justify this - if you can you should believe this answer much more).
'into' is an insertion indicator.
'welsh lake' becomes 'Bala' (Lake Bala is a Welsh lake).
'ac'+'lav'='aclav'
'aclav' inserted within 'bala' is 'BALACLAVA'.
Can you help me to learn more?
(Other definitions for balaclava that I've seen before include "Knitted hat (for bank robbers?)" , "Woollen hat named after a battle" , "helmet no protection against shrapnel" , "Woollen helmet" , "Warm hat" .)