Bird looking a bit guilty when there's a sell-out? (7)
I believe the answer is:
seagull
'bird looking' is the definition.
'seagull' can be an answer for 'bird' (I've seen this before). I'm not sure about the 'looking' bit.
'a bit guilty when there's a sell-out?' is the wordplay.
'bit' indicates taking the first letters (I've seen 'bit of' mean this).
'when' becomes 'u' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'there's' means one lot of letters go next to another.
'out?' indicates putting letters inside.
The first letter of 'guilty' is 'g'.
'a'+'g'+'u'='agu'
'agu' going into 'sell' is 'SEAGULL'.
Can you help me to learn more?
(Other definitions for seagull that I've seen before include "Main creature" , "Avian scavenger" , "Marine bird" , "One sitting atop mast perhaps" , "Bird paradoxically fond of landfill sites" .)