قَصِيدَةٌ فَصِيحَةٌ
A fasih poem.
A poem consists of multiple verses and phrases, not necessarily all independent propositions. Describing the poem as fasih does not require every constituent fragment to function as a complete grammatical sentence.
Compare «عَالِمٌ فَاضِلٌ» (a learned, virtuous man: a descriptive expression) with «العَالِمُ فَاضِلٌ» (the scholar is virtuous: a full statement). A poem may contain different kinds of construction, so the technical scope of kalam requires care.