Introduction of naval vessel that's more up-to-date (5)
I believe the answer is:
newer
'more up-to-date' is the definition.
(I've seen this before)
'introduction of naval vessel' is the wordplay.
'introduction of' indicates taking the first letters.
'vessel' becomes 'ewer' (ewer is a kind of vessel).
The initial letter of 'naval' is 'n'.
'n'+'ewer'='NEWER'
'that's' is the link.
(Other definitions for newer that I've seen before include "More current" , "More modern" , "More recent" , "More up-to-date" , "Fresher, not as old" .)