Become denser (7)
I believe the answer is:
thicken
(Other definitions for thicken that I've seen before include "(Of a plot) become more complicated" , "Become more dense (as plots do)" , "Become more viscous" , "Make less flowing" , "Clot" .)
I believe the answer is:
thicken
(Other definitions for thicken that I've seen before include "(Of a plot) become more complicated" , "Become more dense (as plots do)" , "Become more viscous" , "Make less flowing" , "Clot" .)