Amongst the tracklist, the only one that I feel could be "The Clover" (the instrumental) is Behind The Veil.
Tracks 1 and 9 are out (1 is YARRG, 9 seems like the epic). The looking glass has lyrics, so does the enemy within and along for the ride (from the videos).
The bigger picture & surrender to reason seem very literal song titles straight out of a chorus, and DT instrumentals tend to have more abstract names(IMO).
That leaves enigma machine and behind the veil.
Now, while I don't think they'd write a song about the actual Enigma Machine, clovers are associated with irish folklore, and that's somewhat akin to Behind The Veil.
//speculate off.