It's in fashion, a lot, for linking computers (5)
I believe the answer is:
modem
'linking computers' is the definition.
I can't tell whether this definition defines the answer.
'it's in fashion a lot' is the wordplay.
I cannot quite see how this works, but
'fashion' could be 'mode' (synonyms) and 'mode' is found in the answer.
'lot' could be 'm' and 'm' is present in the answer.
No letters remain.
This explanation may well be incorrect...
'for' is the link.
Can you help me to learn more?
(Other definitions for modem that I've seen before include "Communications device" , "Computer interface" , "Device for connecting two computers" , "Device for connecting computers via a phone line" , "Device linking computers via a telephone line" .)