Condition of tank perhaps after attack from the air (6)
I believe the answer is:
rusted
'after attack from the air' is the definition.
I can't tell whether this defines the answer.
'condition of tank' is the wordplay.
'condition' becomes 'rust' (rust is a kind of condition).
'of tank' becomes 'ed' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'rust'+'ed'='RUSTED'
'perhaps' acts as a link.
Can you help me to learn more?
(Other definitions for rusted that I've seen before include "Corroded" , "(Of iron) oxidised" .)