The ones the holes are in (5)
I believe the answer is:
those
'holes are in' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'the ones' is the wordplay.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'ones' becomes 'hose' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
't'+'hose'='THOSE'
'the' is the link.
Can you help me to learn more?
(Other definitions for those that I've seen before include "Plural form of that" , "The (things) there" , "the more far out?" , "The ones farther away" , "Nostalgic utterance" .)