No-frills airline defective but let's go with it (5)
I believe the answer is:
basic
'no-frills' is the definition.
(I've seen this in another clue)
'defective but let's go with it' is the wordplay.
'defective' means to remove the last letter (the word is broken and incomplete).
'but' becomes 'bar' (both can mean 'excluding' or 'except').
'let's go' becomes 'sic' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with it' says to put letters next to each other.
'bar' with its last letter removed is 'ba'.
'ba'+'sic'='BASIC'
'airline' acts as a link.
This may not be correct. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for basic that I've seen before include "Fundamental; alkaline" , "Spartan" , "Simple, unadorned" , "Plain" , "Fundamental, forming a starting-point" .)