Denial of chart is particularly significant (7)
I believe the answer is:
notable
'particularly significant' is the definition.
'notable' can be an answer for 'significant' (I've seen this before). I'm unsure of the 'particularly' bit.
'denial of chart' is the wordplay.
'denial of' becomes 'no' (I can't explain this - if you can you should give a lot more credence to this answer).
'chart' becomes 'table' (a table of information).
'no'+'table'='NOTABLE'
'is' is the link.
Can you help me to learn more?
(Other definitions for notable that I've seen before include "Worthy of attention, significant" , "celebrity" , "Impressive" , "Outstanding" , "Big noise" .)