Tracked vehicles carrying head of Hull's TA (6)
I believe the answer is:
thanks
'ta' is the definition.
(I've seen this before)
'tracked vehicles carrying head of hull's' is the wordplay.
'tracked vehicles' becomes 'tanks' (tank is a kind of vehicle. I am not sure about the 'tracked' bit.).
'carrying' means one lot of letters goes inside another.
'head of' says to take the initial letters.
The initial letter of 'hulls' is 'h'.
'tanks' enclosing 'h' is 'THANKS'.
Can you help me to learn more?
(Other definitions for thanks that I've seen before include "Cheers" , "Much obliged!" , "Expressions of gratitude" , "recognition?" , "Word of gratitude" .)