"Clearer" would usually be correct - example; "the sky is clearer than yesterday". A rule I learnt in school is that only words with more than two syllables should have "more". However, there are some sentences where you might use "more clear" instead; Example; "Can you make it more clear for me?"

ONE SYLLABLE ADJECTIVE COMPARATIVE ADJECTIVE SUPERLATIVE ADJ TALL TALLER TALLEST CLEAR CLEARER CLEAREST BIG BIGGER BIGGEST CANT SAY MORE CLEAR OR MORE CLEARER OR MORE CLEAREST CAN SAY CAREFUL MORE CAREFUL MOST CAREFUL IMPORTANT MORE IMPORTANT MOST IMPORTANT I HOPE IT HELPS YOU

clearer

Chrisa, I think that even in your example I would say "clearer"