Giants, in the main, take on girls anyhow (not good!) (3,7)
I believe the answer is:
oil tankers
'giants' is the definition.
I know nothing about this answer so I can't tell whether this works.
'the main take on girls anyhow not good' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'take' could be 'r' (abbreviation for 'recipe', Latin for 'take') and 'r' is found in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Another definition for oil tankers that I've seen is " merchant vessels".)