Letter to publish as a mere fabrication (6)
I believe the answer is:
tissue
'a mere fabrication' is the definition.
'tissue' can be an answer for 'fabrication' (thesaurus). I'm not certain of the 'a mere' bit.
'letter to publish' is the wordplay.
'letter' becomes 't'.
'to publish' becomes 'issue' ('issue' can be a synonym of 'publish').
't'+'issue'='TISSUE'
'as' acts as a link.
Can you help me to learn more?
(Other definitions for tissue that I've seen before include "Thin paper; concoction (of lies)" , "Maybe lies" , "cellular network" , "Flimsy paper" , "Disposable piece of absorbent paper" .)